Tire uniformity machines, also referred to as tire uniformity optimizers (TUO) or tire uniformity graders (TUG), have been developed and are used in the tire industry for accurately measuring and grading the radial and lateral force variations, conicity and ply steer found within a cured tire. It also has the ability to analyze test data and to correct for certain nonuniformities in the tire. These machines consist of a load carrying structure, precision rims and a loadwheel. Top and bottom rims hold and rotate the tire and the loadwheel, which is mounted on loadcells, applies force to the inflated tire and detects force variations in the tire. The loadcells provide signals and test results to an operator of the machine to indicate the condition of the tire and to take corrective measures if possible. The readouts from the loadcell provide very accurate measurements of tire characteristics. The accuracy of these measurements is based upon the correct parallelism and squareness of the machine spindle with the circumferential surface of the loadwheel. After a certain number of operations it is necessary to recheck the parallelism and squareness of the loadwheel with respect to the machine spindle to insure continued accuracy of the readouts. However, monitoring minor adjustments is required periodically to maintain this parallelism and squareness. Heretofore, in order to measure these parameters, the rims of the chuck assembly and spindle adaptor had to be removed and an alignment adaptor shaft was placed on the spindle shaft, and a single dial indicator was then moved between top and bottom of the loadwheel surfaces on the spindle shaft adaptor to obtain the alignment readings. However, a considerable amount of time and work was required for the removal of the chuck rims and placement of the spindle adaptor shaft on the spindle shaft in order to take the measurement readings. Another sensor then could be mounted on the spindle adaptor shaft for checking the squareness of the loadwheel with respect to the spindle shaft.
Since the dismantling of the machine, and in particular, components of the chuck assembly, is a relatively time consuming and tedious operation, the need exists for an improved device or fixture for accurately measuring the parallelism and squareness of a loadwheel circumferential surface with respect to the spindle assembly of a tire uniformity machine without requiring dismantling of the machine, yet without sacrificing accuracy of the alignment readings.
Various types of test apparatus and fixtures have been developed for insuring the alignment of various types of machines and equipment, examples of which are shown in the following patents.
U.S. Pat. No. 4,417,237 discloses an apparatus and method for detecting and indicating misalignment of vehicle wire spoke wheels wherein a circuit is mounted at the bottom part of the wheel and includes left and right misalignment sensors which detect misalignment of a portion of the rim when the rim is rotated.
U.S. Pat. No. 2,613,447 discloses a testing device for checking the alignment and the eccentricity of automobile wheels, axles and brake drums. A sensor wheel contacts the outer rim of the rotating member and rotates about a pivot to indicate any eccentricity on the member being tested.
U.S. Pat. No. 3,128,561 discloses an apparatus for measuring wheel alignment which uses a pair of rods attached to conductive brushes. An electrical meter is connected to the brushes and indicates the potential differences between two connections which are representative of the parallelism between the wheels.
U.S. Pat. No. 4,660,294 discloses a surface alignment apparatus having an upstream turbine wheel and a downstream turbine wheel positioned relative to a stepped shaft. The measurements taken between faces of the wheels are taken by extensometers which indicate parallelism of the two faces.
U.S. Pat. No. 2,929,147 discloses a device for checking dimensional variations or unevenness of surface portions of an annular article. The checking device includes contact members which are positioned to engage circumferentially spaced portions of the inner braking surface of the liner at a predetermined distance from each other. A gauge head is connected to a power unit which is electrically connected to a meter to detect variations in the article surfaces.
None of the above discussed prior art patents, or other known prior art, is believed to show or describe an alignment fixture which achieves these advantages of the present invention which is described in detail below.